export default {
  bind(el, binding, vnode) {
    // 查找border组件的头部元素
    const headerEl = el.querySelector('.headsBorders')
    const dragDom = el
    const vnodes = vnode

    if (headerEl) {
      headerEl.style.cssText += ';cursor:move;'

      // 获取原有属性
      const getStyle = (
        window.document.currentStyle
          ? (dom, attr) => dom.currentStyle[attr]
          : (dom, attr) => getComputedStyle(dom, false)[attr]
      )

      headerEl.onmousedown = (e) => {
        // 鼠标按下，计算当前元素距离可视区的距离
        const disX = e.clientX - headerEl.offsetLeft
        const disY = e.clientY - headerEl.offsetTop

        const dragDomWidth = dragDom.offsetWidth
        const dragDomHeight = dragDom.offsetHeight

        const screenWidth = document.body.clientWidth
        const screenHeight = document.body.clientHeight

        const minDragDomLeft = dragDom.offsetLeft
        const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

        const minDragDomTop = dragDom.offsetTop
        const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomHeight

        // 获取到的值带px 正则匹配替换
        let styL = getStyle(dragDom, 'left')
        let styT = getStyle(dragDom, 'top')

        if (styL.includes('%')) {
          styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100)
          styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100)
        } else {
          styL = +styL.replace(/\px/g, '')
          styT = +styT.replace(/\px/g, '')
        }

        document.onmousemove = function (e) {
          // 通过事件委托，计算移动的距离
          let left = e.clientX - disX
          let top = e.clientY - disY

          // 边界处理
          if (-(left) > minDragDomLeft) {
            left = -minDragDomLeft
          } else if (left > maxDragDomLeft) {
            left = maxDragDomLeft
          }

          if (-(top) > minDragDomTop) {
            top = -minDragDomTop
          } else if (top > maxDragDomTop) {
            top = maxDragDomTop
          }

          // 移动当前元素
          dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`
          // 触发拖动事件
          if (vnodes.child) {
            vnodes.child.$emit('drag', e)
          }
        }

        document.onmouseup = function () {
          document.onmousemove = null
          document.onmouseup = null
        }
      }
    }
  }
}
